Maybe a bit of off topic but since it's winter wheel/tire related thing, I'll post here for you guys to share.
Found some interesting winter wheel setup from RealOEM.
18x8 ET20 all around are what BMW uses for E9X M3 winter setup but couldn't find the tire size info.
X5M: Dinan Exhaust | Dinan Suspension | Velos Tune | BMW Perfomance Splitter | Lux V4 | Euro Mirrors | H&R 12/25 mm Spacers | IND Cosmetic Package
PAST: 08 E90 M3 | 08 E92 335i | 03.5 E46 M3 | 99 E36 M3